Method for providing secure data transfer in a mesh network

Abstract

A mesh network comprises a plurality of data nodes (a-g, e) configured to make direct data transfers to all other nodes (a-g, e) in the network within transmission range. The invention provides a method for making a secure data transfer from one node to another. Each node has already measured the exact time-of-flight to its neighbours and this information has been supplied to the coordinator node (1) or to the transmitting node (s). The transmitting node (s) can determine the time-of-flight along a number of different routes (A-E) through the mesh. The data to be transmitted is chopped up such that the data taking the longest route (E) is sent first, and the data taking the shortest route (A) is sent last. At the receiving end, the data arrives exactly re-ordered in time, and thus no decoding needs to take place. The benefit of this is that even if the transmitting end (s) is monitored, the data (I-V) has already been chopped up when it is transmitted, and at the receiving end (d), the data cannot be interpreted unless co-located onto the same receiving spot, as that is the only place in which the data arrives at the exact time synchronised moment.

1 . A method of transmitting a message comprising a sequence of ordered data portions (I-V) between a source node (s) and a destination node (d) in a network, the method comprising 
 assigning a route from a plurality of different routes (A-E) to each of the data portions (I-V), and    transmitting each of the data portions (I-V) at a specific time based on the assigned route and order such that the portions are received in the ordered sequence at the destination node (d).    
   
   
       2 . The method of  claim 1  further comprising the source node (s) not being within the transmission range of the destination (d) node and each route (A-E) comprising at least one node (a-c, e-g) for forwarding the data portion.  
   
   
       3 . The method of  claim 2 , wherein said data portion comprises route data ( 29 ) specifying the addresses of the at least one node along the route (a-c, e-g).  
   
   
       4 . The method of  claim 3  further comprising each of the at least one node (a-c, e-g) along the route receiving the data portion (I-V), checking said route data ( 29 ) associated with the data portion and forwarding the portion to the next node indicated by said route data.  
   
   
       5 . The method of  claim 4  wherein the data portion and the route data are included in a Media Access Control data frame ( 25 - 32 ).  
   
   
       6 . The method of  claim 1 , wherein each route (A-E) is selected with consideration to the information on the distances between nodes in the network.  
   
   
       7 . The method of  claim 1 , wherein the network has a coordinator node ( 1 ) and the coordinator stores the information on the distances between nodes in the network in the storage ( 6 ) of the coordinator node.  
   
   
       8 . The method of  claim 7  wherein said information stored in the network coordinator is changed in response to a change in position of a network node.  
   
   
       9 . The method of  claim 7  wherein the source node (s) is not the network coordinator, the source node (s) requests route data to a destination node (d) from the network coordinator ( 1 ) and the coordinator sends route data to the source node.  
   
   
       10 . The method of  claim 9  wherein the route data comprises a plurality of available routes between the source node and the destination node and the time of flight of data along each of the plurality of routes ( 39 ,  40 ,  41 ).  
   
   
       11 . The method of  claim 10  wherein the route data further comprises the information about which route is assigned to each data portion and when to transmit each of the data portions ( 42 , 43 , 44 ).  
   
   
       12 . The method of  claim 1  wherein the data portion assigned the longest route is transmitted first.  
   
   
       13 . The method of  claim 1  wherein the data portion assigned the shortest route is transmitted last.  
   
   
       14 . The method according to  claim 1  wherein the data portions are assigned routes in dependence on said order of the data portion in the ordered sequence.  
   
   
       15 . The method according to  claim 14  wherein a data portion from the beginning of the ordered sequence is assigned a longer route than a data portion from the end of the ordered sequence.  
   
   
       16 . The method according to  claim 1  wherein the data is sent using the IEEE 802.15.4 protocol ( 16 ,  17 ).  
   
   
       17 . The method according to  claim 1  wherein the data is sent using the ZigBee standard.  
   
   
       18 . A device ( 1 ,  10 ) adapted to be used in a wireless network comprising a plurality of nodes for transmitting a message comprising an ordered sequence of data portions (I-V) through the network to a destination node (d) comprising 
 transmission means ( 2 ,  11 ) for transmitting each of the data portions (I-V) along a different route (A-E) and at a different time based on said route and order such that the data portions (I-V) are received in the ordered sequence at the destination node (d).    
   
   
       19 . The device ( 1 ,  10 ) as in  claim 18 , further having storage means ( 6 ,  14 ) for storing data about the distance between individual nodes in the network, 
 calculation means ( 4 ,  12 ) for calculating the time-of-flight along a plurality of routes between a source node and a destination node in the network, and    selecting means ( 4 ,  12 ) for selecting a route for each of said data portions, wherein    the calculation means are further configured to calculate the time of transmission of each data portions such that the portions arrive at the destination node in the ordered sequence.    
   
   
       20 . The device ( 1 ,  10 ) according to  claim 18  wherein the device is a ZigBee device or a Bluetooth device.  
   
   
       21 . The device ( 1 ,  10 ) according to  claim 18  wherein the device operates according to the IEEE 802.15.4 standard.  
   
   
       22 . A network comprising a plurality of nodes as claimed in  claim 18 .  
   
   
       23 . A network as in  claim 22  comprising a mesh network.  
   
   
       24 . A network as in  claim 22  wherein the plurality of nodes includes a coordinating node for supplying route information to other nodes when requested.